I’ve mentioned before that Colin designed this house to be as energy-efficient as possible. In particular, we will maximize insulation by building the exterior walls 11½ inches thick. Structurally, it’s a double wall: 2×6 construction on the outer wall, 2×4 construction on the inner wall, with a 2½-inch space in between. (How does that add up to 11½ inches? See this post.) We built the 2×6 walls long ago, since they support the floors and the roof. Now we’re going back inside to build the 2×4 walls.

Top view showing the double wall configuration. It’s almost like building the house twice!

Here’s what the double wall looks like as built.

We found a clever way to ensure the 2×4 walls went up in the right locations, a constant 2½ inches from the 2×6 walls. Colin cut a whole bunch of scrap plywood into 2½-inch spacers, and we nailed them to the floor and ceiling. To ensure a strong connection, we installed the second top plate directly to the ceiling, then raised the rest of the wall to squeeze between the floor and the plate. We made our lives even easier by nailing blocks to the second top plate, which helped guide the wall into place.

Carson installs spacers on the ceiling. To his right, part of the 2×4 wall has been raised already.

The crew raised the first 2×4 walls before installing any windows. To make the windows fit more easily, Terry suggested leaving out the rough opening lumber and just building the layout studs (16 inches on center) at first. Then, once we put the windows in, we measured the window frames and their locations relative to the top and bottom plates. Those measurements allowed us to cut and assemble the headers, sills, jack studs, cripples, and king studs to fit neatly around.

This sequence leads to a lot of interesting situations. I find in some locations that the layout studs were built less than 3 inches – the thickness of two 2x4s – from the window frame. Therefore I can’t fit both a jack stud and a king stud next to the window. I need to leave out the outer stud, so to make up for it I extend the header and sill to frame directly into the layout stud. Cripples need to be toenailed into the top and bottom plates, often at funny angles because access is so limited. Most frustrating, sometimes the window frame isn’t quite square to the wall. All the windows are perfectly level – we checked – but apparently the 2×4 walls are not. The challenge is assembling the rough opening large enough to fit around the window at the tightest spots but not so spacious as to hinder the installation of drywall and interior trim later.

2×4 frames built to fit around the windows.

Plan for the week ahead is to finish the double walls and as many interior walls as possible. Now that the house is dry, we’ve begun to schedule subcontractors for plumbing and wall-finishing, and we need to get the interior ready for them. Also, the door delivery comes tomorrow!